Nice work!! Looks awesome!
Your rubber inserts on the sides of your transmission crossmember look odd? The crossmember should fit inside a slot located in the rubber insulators wrapped with the metal brackets. Might be worth double checking there fitment as they could raise that section as well.
Gotta say x2 on this one. That left trans crossmember mount looks odd in the photo. What's up with the large bolt and nut?
Here is what the rubber insulator should look like in pic #1
. The metal brackets that hold it in place and bolt to the frame are seen in pic #2
. The flat ear found on the end of the trans crossmember slides into the rubber insulator and then the metal bracket goes over the top and bolts to the frame rails.
The mount under the transmission case could be thicker than original as aftermarket pieces can be incorrect. I assume it has been replaced? If you had an original to measure by, you would know. Also the trans looks in the photo to be off center to the left. It may be the photo. The 2 bolts that attach the trans mount to the transmission go through the crossmember. These holes are slotted/elongated so you can center the transmission. You may want to check this.
My 1968 Lemans (3-speed manual trans) front U-joint used to hit my floor every once in a while. It seemed to do it mostly when I put a passenger in the seat. My car was jacked up a little in the rear and I ran 14" tires up front and 15" out back. I had new U-joints and driveshaft/rear was original. It is possible that the bushing were worn out in the rear/control arms allowing the rear end to twist upward or move around when extra weight in the form of a passenger(s) was added and changed the driveshaft angle which in turn may have been the cause. I also went with a polyurethane trans mount which could have been thicker than factory.
Did not do it enough to worry about as I rarely had a passenger. I looked a couple of times and never saw anything evident that stood out, but I also never checked the rear bushings as I knew they were original and worn, nor did I check pinion/driveshaft angles. Drove it this way for about 7-8 years.